Since 2004, as per the Road Vehicles (Construction & Use) Regulations, the prescribed visible light transmission level for windows forward of the ‘B’ Post are as follows;
Motor Vehicles first used before 1 April 1985:
The windscreen and front side windows must allow at least 70% of light to be transmitted through them.
Motor Vehicles first used on or after 1 April 1985:
The light transmitted through the windscreen must be at least 75%.
The front side windows must allow at least 70% of light to be transmitted through them.